1. Field of the Invention
This invention relates to an information memory and display medium, and more particulary to an information memory and display medium capable of storing information in its magnetic recording layer, displaying the stored information in its reversible thermosensitive recording layer, and erasing the displayed information.
2. Discussion of Background
A "prepaid card" is now enjoying tremendous popularity, which is used instead of cash or token coins, for instance, for a public telephone and an automatic ticket vending apparatus for bus, train or subway.
In such a prepaid card, information regarding the spendable sum is recorded therein in advance. The card is punched when it is used in accordance with the amount spent, and a user can roughly know the balance by the punched hole in combination with figures previously printed on the surface of the card.
In order to precisely know the balance, a prepaid card which can display on its surface the balance in figures has been devised. Such a card comprises a thermosensitive recording layer containing a leuco dye or a thermosensitive recording layer prepared by depositing Sn on a magnetic recording layer, as disclosed in Japanese Laid-Open Patent Applications 59-199284 and 60-18388, and the figures for the balance are displayed on its surface when heat is applied thereto by a thermal head. The prepaid card of this type, however, has a shortcoming in that once displayed images cannot be erased.
In order to eliminate the above shortcoming, the inventors of the present invention have proposed an information memory and display medium comprising a thermosensitive recording layer of which transparency is reversibly changeable depending upon its temperature. Owing to such properties of the thermosensitive recording layer, images once recorded therein can be erased. In this medium, the memory function is resided on one surface of the medium and the display function, on the other surface. Therefore, when such a medium is used as a prepaid card, the card has no extra surface usable for advertisement or the like.